Submersible pumping systems with intake modules having tangential fluid intake ports

This invention relates generally to the field of downhole pumping systems, and more particularly to systems and methods for optimizing pumping operations in wells with a high gas-to-liquid ratio.

Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the wellbore fluids from the subterranean reservoir to a storage facility on the surface. In many cases, the pump assemblies are multistage centrifugal pumps that include a plurality of stages, with each stage including a stationary diffuser and a rotary impeller that is connected to a shaft driven by the electric motor.

Hydrocarbon fluids produced from subterranean wells often include liquids and gases. Although both may be valuable, the multiphase flow may complicate recovery efforts. For example, naturally producing wells with elevated gas fractions may overload phase separators located on the surface. This may cause gas to be entrained in fluid product lines, which can adversely affect downstream storage and processing.

In wells in which artificial lift solutions have been deployed, excess amounts of gases and solids in the wellbore fluid can present problems for downhole equipment that is primarily designed to produce liquid-phase products. In particular, fluid with a high gas-to-liquid ratio (“GLR”) or gas volume fraction (“GVF”) may adversely impact efforts to recover liquid hydrocarbons with pumping equipment. Liquid “slugging” occurs when large pockets of gas alternated with liquid slugs develop while the fluid flows to surface.

The centrifugal forces exerted by downhole turbomachinery tend to separate gas from liquid, thereby increasing the chances of gas interference or vapor lock. Downhole gas separators have been used to remove gas before the wellbore fluids enter the pump. In operation, wellbore fluid is drawn into the gas separator through an intake. A lift generator provides additional lift to move the wellbore fluid into an agitator. The agitator is typically configured as a rotary paddle that imparts centrifugal force to the wellbore fluid. As the wellbore fluid passes through the agitator, heavier liquid components, such as oil and water, are carried to the outer edge of the agitator blade, while lighter gaseous components remain closer to the center of the agitator. In this way, modern gas separators take advantage of the relative difference in specific gravities between the various components of the two-phase wellbore fluid to separate gas from liquid. Once separated, the liquid can be directed to the pump assembly and the gas vented to the wellbore from the gas separator.

In other cases, the downhole electric submersible pumping system is provided with a specialized intake that includes a gravity-based separation mechanism in which multi-phase fluids are drawn into the bottom of an intake chamber in which gases are allowed to escape from the top of the chamber and liquids are drawn downward before being directed back up toward the pump. This tortuous path separation system can be effective in lower production volume wells, but in higher flow rate applications the multi-phase fluid is moving too fast to permit gravity separation of the liquid and gases. There is, therefore, a need for an improved intake system for handling fluids with a high gas-to-liquid ratio.

In some embodiments, the present disclosure is directed to a submersible pumping system for producing a fluid from a wellbore through production tubing to a wellhead, where the pumping system includes a motor, a production pump driven by the motor, and an intake module between the motor and the production pump. The intake module includes a housing, a first stage chamber inside the housing, and a second stage chamber inside the first stage chamber. The second stage chamber is in fluid communication with the production pump. The intake module further includes a plurality of tangential fluid intake ports that extend from the wellbore through the housing into the first stage chamber, and a plurality of gas discharge ports that extend from the wellbore to the first stage chamber. The plurality of gas discharge ports are located above the plurality of tangential fluid intake.

In other embodiments, the present disclosure is directed at a submersible pumping system for producing a fluid from a wellbore through production tubing to a wellhead, where the pumping system includes a motor, a production pump driven by the motor, and a pair of intake modules connected together in a tandem configuration. A first (lower) intake module includes a housing, a first stage chamber inside the housing, a second stage chamber inside the first stage chamber, a plurality of tangential fluid intake ports that extend from the wellbore through the housing into the first stage chamber, and a plurality of gas discharge ports that extend from the wellbore to the first stage chamber. The plurality of gas discharge ports are located above the plurality of tangential fluid intake.

The second (upper) intake module is between the first intake module and the production pump. The second intake module includes a housing, a first stage chamber inside the housing and a second stage chamber inside the first stage chamber. The first stage chamber of the second intake module is in fluid communication with the second stage chamber of the first intake module and the second stage chamber of the second intake module is in fluid communication with the production pump. The second intake module also includes a plurality of tangential fluid intake ports that extend from the wellbore through the housing into the first stage chamber and a plurality of gas discharge ports that extend from the wellbore to the first stage chamber. The plurality of gas discharge ports are located above the plurality of tangential fluid intake.

In yet other embodiments, the present disclosure is directed to a submersible pumping system for producing two-phase fluids from a well, where the pumping system includes a motor, a seal section connected to the motor, a production pump driven by the motor, and an intake module between the seal section and the production pump. The intake module includes a housing, a first stage chamber inside the housing, and a second stage chamber inside the first stage chamber. The second stage chamber is in fluid communication with the production pump. The intake module further includes a plurality of tangential fluid intake ports that extend from the wellbore through the housing into the first stage chamber. The plurality of tangential fluid intake ports are configured to induce a swirling motion of two-phase fluid in the first stage chamber. The intake module also includes a plurality of gas discharge ports that extend from the wellbore to the first stage chamber, where the plurality of gas discharge ports are located above the plurality of tangential fluid intake.

As used herein, the term “petroleum” refers broadly to all mineral hydrocarbons, such as crude oil, gas and combinations of oil and gas. The term “fluid” refers to both gases and liquids and the term “two-phase” refers to a fluid that includes a mixture of gases and liquids. It will be appreciated by those of skill in the art that, in the downhole environment, a two-phase fluid may also carry solids and suspensions. Accordingly, as used herein, the term “two-phase” not exclusive of fluids that contain liquids, gases, solids, or other intermediary forms of matter.

depicts a pumping systemattached to production tubing. The pumping systemand production tubingare disposed in a wellbore, which is drilled for the production of a fluid such as water or petroleum. The production tubingconnects the pumping systemto a wellheadlocated on the surface. Although the pumping systemis primarily designed to pump petroleum products, it will be understood that the present invention can also be used to move other fluids. It will also be understood that, although each of the components of the pumping system are primarily disclosed in a submersible application, some or all of these components can also be used in surface pumping operations. Although the wellboreis depicted as a wellbore that includes vertical and lateral portions, it will be appreciated that the pumping systemcan also be deployed in wellbores with other configurations.

For the purposes of the disclosure herein, the terms “upstream” and “downstream” shall be used to refer to the relative positions of components or portions of components with respect to the general flow of fluids produced from the wellbore. “Upstream” refers to a position or component that is passed earlier than a “downstream” position or component as fluid is produced from the wellbore. The terms “upstream” and “downstream” are not necessarily dependent on the relative vertical orientation of a component or position. It will be appreciated that many of the components in the pumping systemare substantially cylindrical and have a common longitudinal axis that extends through the center of the elongated cylinder and a radius extending from the longitudinal axis in a lateral plane to an outer circumference. Objects and motion may be described in terms of axial, longitudinal, lateral, or radial positions within components in the pumping system.

In the embodiment depicted in, the pumping systemincludes a production pump, a motor, a seal section, and an intake module. The seal sectionis connected to a downstream end of the motor. The seal sectionis positioned between the motorand intake module. The seal sectionshields the motorfrom mechanical thrust and accommodates the expansion of motor lubricants during operation. The seal sectionand motorcan be presented as a single, integrated unit or as two distinct components connected together.

The motorreceives electrical power through a power cable connected to a power source and motor drive on the surface. When energized, the motortransfers torque to the production pumpthrough a series of interconnected shafts extending from the motorto the production pumpthrough the seal section, intake module, and any additional intervening components. The motorcan be an induction motor or a permanent magnet motor. The pumping systemoptionally includes a gauge or sensorthat is configured to measure various conditions in the wellbore, including but not limited to temperature, pressure, vibration, and operating conditions within the motor. The annular space surrounding the pumping systemand production tubingin the wellboreis referred to herein as the wellbore annulus.

The intake moduleprovides a path for fluids from the wellbore annulusto enter the pumping system. In the embodiment depicted in, the production pumpis connected to a downstream end of the intake module. In this configuration, fluid entering the production pumpmust first pass through the intake module. Although the intake moduleis depicted as a separate component in, it will be understood that in other embodiments the intake moduleis integrated into the seal section, production pump, or another component adjacent to production pump. In each case, the intake moduleis configured to provide a direct or indirect path for fluid from the wellbore annulusto the production pump, while reducing the gas content in the fluid before the fluid reaches the production pump.

Turning to, shown therein a depictions of the intake module. The intake moduleincludes an outer housingthat surrounds an inner cylinder. An intake module shaftpasses through the inner cylinder. In some embodiments, a shaft support tubesurrounds the intake module shaftinside the inner cylinder. The annular space between the outer housingand the inner cylinderforms a first stage chamber, while the interior of the inner cylinder forms a second stage chamber. The inner cylinderincludes a lower openingand an upper outlet. The upper outletis in direct or indirect fluid communication with the upstream end of the production pump.

The outer housingincludes one or more tangential fluid intake ports, one or more gas discharge ports, and upper cap. The upper capprevents fluid from passing from the first stage chamberinto the production pumpwithout first passing through the second stage chamber.

As illustrated in, the tangential fluid intake portsextend through the cylindrical outer housingalong a tangent such that fluid passing through the tangential fluid intake portsis forced to rotate within the first stage chamber. The tangential fluid intake portsoptionally have a rectangular cross-section, as depicted inand may extend through the outer housingalong a linear path as shown inor curved path as shown in. In each case, the geometry and orientation of the tangential fluid intake portsis intended to direct fluid into the first stage chambersuch that the fluid contacts the outer surface of the inner cylinderand the inner surface of the outer housingwith a low contact angle.

That is, in the embodiment depicted in, each of the tangential fluid intake portshas a cross section bounded by a first side, a second side, a top and a bottom, and a depth extending through the outer housing, that cooperate to define a tangential intake port volume. A vertical plane extending through a center of the tangential fluid intake port volume that is substantially parallel to, or congruent with, the first side or second side of the tangential fluid intake portdoes not intersect a longitudinal axis extending through the center of the outer housing. For tangential fluid intake portsthat have a non-rectangular cross section, for example circular, oval or irregular cross-sections, the central lateral axis extending through the tangential fluid intake portdoes not intersect the central longitudinal axis of the outer housing.

Each of the plurality of tangential fluid intake portsis similarly oriented such that two-phase fluidpassing through the tangential fluid intake portsis encouraged to swirl or rotate within the first stage chamber, in either clockwise or counterclockwise direction. In some embodiments, the tangential fluid intake portsare oriented to induce a swirl in the first stage chamberthat matches the rotation of the intake module shaft. As depicted in, the tangential fluid intake portscan be located along the outer housingat different distances from the production pump. The centrifugal forces generated by the rotation of the fluid inside the first stage chambercauses the denser, liquid-dominant portions of the fluid to collect along the inside surface of the outer housing, while lighter gas-dominant portions of the fluid collect along the outside surface of the inner cylinder.

As illustrated in, the induced swirl rapidly separates liquidsfrom gaseswithin the first stage chamber, with gasesrising along the inside of the first stage chambertoward the upper cap. In the upper portion of the first stage chamber, the accumulating gasescollect and are discharged into the wellbore annulusthrough the gas discharge ports. The gas discharge portscan extend through the outer housingalong a tangential or non-tangential (radial) path.

The liquidswith a reduced gas fraction are pulled to the bottom of the first stage chamberwhere the liquid-dominant fluidenters the second stage chamberthrough the lower opening. The liquid-dominant fluidthen passes through the internal second stage chamberbefore passing into the production pumpthrough the upper outlet. In this way, as the fluids are being pulled downward through the first stage chamber, the lighter gasesare encouraged by gravity and centrifugal force to separate from denser fluids, which are then passed to the production pumpthrough the second stage chamber. The synergistic combination of centrifugal and gravity separation mechanisms allows the intake moduleto remove gasfrom two-phase fluidsmore efficiently than conventional gravity-based intake systems.

Turning to, shown therein is an alternate embodiment of the intake module. In this embodiment, the intake moduleincludes one or more inducersconnected to, and configured for rotation with, the intake module shaft. The intake module shaftis supported by spacer bearingsthat permit the passage of fluid through the second stage chamber. The inducerscan be constructed as spiraled flights connected to the intake module shaftsuch that rotation of the intake module shaftcauses the inducersto act as a progressive cavity, screw-type pump that encourages the movement of low-gas-fraction fluid toward the production pump. In exemplary embodiments, the inducersextend from the intake module shaftto the inside surface of the inner cylinder. In some embodiments, the inner cylinderrotates with the inducersand intake module shaft.

In the embodiment depicted in, the inducershave been replaced with centrifugal pump stagesthat each include an impellerand a diffusers. The impellersare each attached to the intake module shaftand configured for rotation, while the stationary diffusersare connected to the inner cylinder. The impellerscan be configured as radial flow impellers that are well-suited for inducing flow through the intake module. In some embodiments, the intake moduleincludes both inducersand centrifugal pump stagesthat cooperatively push the liquid-dominant wellbore fluids toward the production pump.

Turning to, shown therein is a cross-sectional view of the intake moduleconnected between the production pumpand the seal section. In this embodiment, the seal sectionincludes a seal section headthat is in fluid communication with the first stage chamber. The seal section headincludes a shaft sealaround a seal section shaft, a sand shedderconnected to the seal section shaft, and solid discharge portsin the bottom of the seal section head. During use, heavier solids entrained in the wellbore fluids entering the intake modulefall to the bottom of the intake moduleand enter the seal section head. The sand sheddercan be attached to the seal section shaftand configured to direct the particulate solids toward the solid discharge ports, where the solids can be discharged into the wellbore annulus. The solid discharge portsensure that solids do not accumulate in the bottom of the first stage chamberof the intake moduleto an extent the blocks flow into the second stage chamber.

Turning to, shown therein are various embodiments of the pumping systemin which the intake moduleis combined with other components to provide suitable liquid-gas separation to ensure the production pumpis supplied with an intake stream with a satisfactory liquid-to-gas ratio., for example, depicts the embodiment in which the intake moduleis positioned between the production pumpand the seal section. This is the embodiment also depicted in. In this embodiment, two-phase fluidenters the intake module, which removes gasand passes a liquid-dominant feed streamto the production pump. Solidscan be discharged through the solid discharge ports, which can be located in the bottom of the outer first stage chamber(as illustrated in) or the top of the seal section(as illustrated in).

The embodiment depicted inincludes a gas separatorlocated between the intake moduleand the production pump. The gas separatoris generally configured to remove an additional portion of the gas from the two-phase fluid discharged by the intake module. The gas separatorincludes an internal phase separation mechanismand gas separator discharge ports. The internal phase separation mechanismcan be an active agitator system driven by a shaft connected to the motor(as shown), or a passive, vortex-inducing element that relies on the movement of fluid by the production pump, or a combination of active (driven) and passive separation systems. In each case, the internal phase separation mechanismcan be configured to induce a rotation of the fluid discharged from the intake modulewhich tends to force heavier liquids radially outward while lighter gases remain nearer to the axial center of the gas separator. The internal phase separation mechanismcan include a crossover or similar device to direct the lighter gaseous components from the interior of the gas separatorto the wellbore annulusthrough the gas separator discharge ports, while permitting the denser fluids to pass into the production pump.

The embodiment depicted inalso includes the gas separator, but in this embodiment the pumping systemincludes two intake modulesconnected together in a tandem configuration. The liquid-dominant fluid discharged from the lower intake moduleis passed out of the upper outletof the inner cylinderinto the bottom of the first stage chamberof the upper intake module, where it mixes with fluids that entered the upper intake modulethrough the tangential fluid intake portsof the upper intake module. The gas separatorremoves additional gas from the fluid discharged from the upper outletof the upper intake module. In other embodiments, the pumping systemincludes two or more intake modulesconnected together between the seal sectionand production pump, without the use of an intervening gas separator.

The pumping systemdepicted inincludes a booster pumpbetween the gas separatorand the intake module. In some embodiments, the booster pumpis a multistage centrifugal pump that includes a plurality of stages that each include a stationary diffuser and a rotatable impeller connected to a pump shaft driven by the motor. The impellers and diffusers within the booster pumpcan be configured to homogenize and reduce the volume of gas entrained in the fluid discharged from the intake module. The booster pumpincreases the pressure of the pumped fluids in accordance with well-established pump mechanics in which kinetic energy is imparted to the fluid by the rotating impellers, which is then converted in part to pressure head by the stationary diffusers. As the pressure of the fluid increases through the successive stages of the booster pump, the gases and liquids are blended together and the increased pressure reduces the volume of gases entrained in the fluid.

In some embodiments, the booster pumpincludes a progressive cavity or screw-type pumping mechanism. Some embodiments of the booster pumpinclude both turbomachinery and positive displacement pumping mechanisms. In each case, the booster pumpis used to increase the pressure of the fluid discharged from the intake modulebefore the fluid reaches the gas separatorand production pump. In certain applications, the booster pumpcan be used to provide the gas separatorand production pumpwith sufficient net positive suction head (NPSH) to permit the optimal performance of the production pump. In the embodiment depicted in, the pumping systemincludes tandem intake modulesthat feed liquid-dominant fluid to the booster pump, which forces the fluid through the gas separatorand into the production pump.

It will be appreciated that the various embodiments of the pumping systemdisclosed inare provided as non-limiting examples and that other combinations of the production pump, motor, seal section, intake module, gas separatorand booster pumpare contemplated as falling within the scope of the embodiments discloses herein.

It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.